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DataMapper::Hook::ClassMethods

Public Instance Methods

after(target_method, method_sym = nil, &block) click to toggle source

Inject code that executes after the target instance method.

@param target_method<Symbol> the name of the instance method to inject after @param method_sym<Symbol> the name of the method to run after the

target_method

@param block<Block> the code to run after the target_method

@note

Either method_sym or block is required.

- @api public

# File lib/dm-core/support/hook.rb, line 103
def after(target_method, method_sym = nil, &block)
  install_hook :after, target_method, method_sym, :instance, &block
end
after_class_method(target_method, method_sym = nil, &block) click to toggle source

Inject code that executes after the target class method.

@param target_method<Symbol> the name of the class method to inject after @param method_sym<Symbol> the name of the method to run after the target_method @param block<Block> the code to run after the target_method

@note

Either method_sym or block is required.

- @api public

# File lib/dm-core/support/hook.rb, line 71
def after_class_method(target_method, method_sym = nil, &block)
  install_hook :after, target_method, method_sym, :class, &block
end
args_for(method) click to toggle source

--- Helpers ---

# File lib/dm-core/support/hook.rb, line 376
def args_for(method)
  if method.arity == 0
    "&block"
  elsif method.arity > 0
    "_" << (1 .. method.arity).to_a.join(", _") << ", &block"
  elsif (method.arity + 1) < 0
    "_" << (1 .. (method.arity).abs - 1).to_a.join(", _") << ", *args, &block"
  else
    "*args, &block"
  end
end
before(target_method, method_sym = nil, &block) click to toggle source

Inject code that executes before the target instance method.

@param target_method<Symbol> the name of the instance method to inject before @param method_sym<Symbol> the name of the method to run before the

target_method

@param block<Block> the code to run before the target_method

@note

Either method_sym or block is required.

- @api public

# File lib/dm-core/support/hook.rb, line 87
def before(target_method, method_sym = nil, &block)
  install_hook :before, target_method, method_sym, :instance, &block
end
before_class_method(target_method, method_sym = nil, &block) click to toggle source

Inject code that executes before the target class method.

@param target_method<Symbol> the name of the class method to inject before @param method_sym<Symbol> the name of the method to run before the

target_method

@param block<Block> the code to run before the target_method

@note

Either method_sym or block is required.

- @api public

# File lib/dm-core/support/hook.rb, line 56
def before_class_method(target_method, method_sym = nil, &block)
  install_hook :before, target_method, method_sym, :class, &block
end
class_hooks() click to toggle source
# File lib/dm-core/support/hook.rb, line 148
def class_hooks
  self.const_get("CLASS_HOOKS")
end
define_advised_method(target_method, scope) click to toggle source
# File lib/dm-core/support/hook.rb, line 275
def define_advised_method(target_method, scope)
  args = args_for(method_with_scope(target_method, scope))

  renamed_target = hook_method_name(target_method, 'hookable_', 'before_advised')

  source =           def #{target_method}(#{args})            retval = nil            catch(:halt) do              #{hook_method_name(target_method, 'execute_before', 'hook_stack')}(#{args})              retval = #{renamed_target}(#{args})              #{hook_method_name(target_method, 'execute_after', 'hook_stack')}(retval, #{args})              retval            end          end

  if scope == :instance && !instance_methods(false).any? { |m| m.to_sym == target_method }
    send(:alias_method, renamed_target, target_method)

    proxy_module = Module.new
    proxy_module.class_eval(source, __FILE__, __LINE__)
    self.send(:include, proxy_module)
  else
    source = %{alias_method :#{renamed_target}, :#{target_method}\n#{source}}
    source = %{class << self\n#{source}\nend} if scope == :class
    class_eval(source, __FILE__, __LINE__)
  end
end
define_hook_stack_execution_methods(target_method, scope) click to toggle source

Defines two methods. One method executes the before hook stack. The other executes the after hook stack. This method will be called many times during the Class definition process. It should be called for each hook that is defined. It will also be called when a hook is redefined (to make sure that the arity hasn't changed).

# File lib/dm-core/support/hook.rb, line 226
def define_hook_stack_execution_methods(target_method, scope)
  unless registered_as_hook?(target_method, scope)
    raise ArgumentError, "#{target_method} has not be registered as a hookable #{scope} method"
  end

  hooks = hooks_with_scope(scope)

  before_hooks = hooks[target_method][:before]
  before_hooks = before_hooks.map{ |info| inline_call(info, scope) }.join("\n")

  after_hooks  = hooks[target_method][:after]
  after_hooks  = after_hooks.map{ |info| inline_call(info, scope) }.join("\n")

  before_hook_name = hook_method_name(target_method, 'execute_before', 'hook_stack')
  after_hook_name  = hook_method_name(target_method, 'execute_after',  'hook_stack')

  hooks[target_method][:in].class_eval           #{scope == :class ? 'class << self' : ''}          private          remove_method :#{before_hook_name} if instance_methods(false).any? { |m| m.to_sym == :#{before_hook_name} }          def #{before_hook_name}(*args)            #{before_hooks}          end          remove_method :#{after_hook_name} if instance_methods(false).any? { |m| m.to_sym == :#{after_hook_name} }          def #{after_hook_name}(*args)            #{after_hooks}          end          #{scope == :class ? 'end' : ''}, __FILE__, __LINE__ + 1
end
hook_method_name(target_method, prefix, suffix) click to toggle source

Generates names for the various utility methods. We need to do this because the various utility methods should not end in = so, while we're at it, we might as well get rid of all punctuation.

# File lib/dm-core/support/hook.rb, line 196
def hook_method_name(target_method, prefix, suffix)
  target_method = target_method.to_s

  case target_method[-1,1]
    when '?' then "#{prefix}_#{target_method[0..-2]}_ques_#{suffix}"
    when '!' then "#{prefix}_#{target_method[0..-2]}_bang_#{suffix}"
    when '=' then "#{prefix}_#{target_method[0..-2]}_eq_#{suffix}"
    # I add a _nan_ suffix here so that we don't ever encounter
    # any naming conflicts.
    else "#{prefix}_#{target_method[0..-1]}_nan_#{suffix}"
  end
end
hooks_with_scope(scope) click to toggle source

Returns the correct HOOKS Hash depending on whether we are working with class methods or instance methods

# File lib/dm-core/support/hook.rb, line 140
def hooks_with_scope(scope)
  case scope
    when :class    then class_hooks
    when :instance then instance_hooks
    else raise ArgumentError, 'You need to pass :class or :instance as scope'
  end
end
inline_call(method_info, scope) click to toggle source

Returns ruby code that will invoke the hook. It checks the arity of the hook method and passes arguments accordingly.

# File lib/dm-core/support/hook.rb, line 263
def inline_call(method_info, scope)
  DataMapper::Hook::ClassMethods.hook_scopes << method_info[:from]
  name = method_info[:name]
  if scope == :instance
    args = method_defined?(name) && instance_method(name).arity != 0 ? '*args' : ''
    %(#{name}(#{args}) if self.class <= DataMapper::Hook::ClassMethods.object_by_id(#{method_info[:from].object_id}))
  else
    args = respond_to?(name) && method(name).arity != 0 ? '*args' : ''
    %(#{name}(#{args}) if self <= DataMapper::Hook::ClassMethods.object_by_id(#{method_info[:from].object_id}))
  end
end
install_hook(type, target_method, method_sym, scope, &block) click to toggle source

--- Add a hook ---

# File lib/dm-core/support/hook.rb, line 307
def install_hook(type, target_method, method_sym, scope, &block)
  assert_kind_of 'target_method', target_method, Symbol
  assert_kind_of 'method_sym',    method_sym,    Symbol unless method_sym.nil?
  assert_kind_of 'scope',         scope,         Symbol

  if !block_given? and method_sym.nil?
    raise ArgumentError, "You need to pass 2 arguments to \"#{type}\"."
  end

  if method_sym.to_s[-1,1] == '='
    raise ArgumentError, "Methods ending in = cannot be hooks"
  end

  unless [ :class, :instance ].include?(scope)
    raise ArgumentError, 'You need to pass :class or :instance as scope'
  end

  if registered_as_hook?(target_method, scope)
    hooks = hooks_with_scope(scope)

    #if this hook is previously declared in a sibling or cousin we must move the :in class
    #to the common ancestor to get both hooks to run.
    if !(hooks[target_method][:in] <=> self)
      before_hook_name = hook_method_name(target_method, 'execute_before', 'hook_stack')
      after_hook_name  = hook_method_name(target_method, 'execute_after',  'hook_stack')

      hooks[target_method][:in].class_eval               remove_method :#{before_hook_name} if instance_methods(false).any? { |m| m.to_sym == :#{before_hook_name} }              def #{before_hook_name}(*args)                super              end              remove_method :#{after_hook_name} if instance_methods(false).any? { |m| m.to_sym == :#{before_hook_name} }              def #{after_hook_name}(*args)                super              end, __FILE__, __LINE__ + 1

      while !(hooks[target_method][:in] <=> self) do
        hooks[target_method][:in] = hooks[target_method][:in].superclass
      end

      define_hook_stack_execution_methods(target_method, scope)
      hooks[target_method][:in].class_eval{define_advised_method(target_method, scope)}
    end
  else
    register_hook(target_method, scope)
    hooks = hooks_with_scope(scope)
  end

  #if  we were passed a block, create a method out of it.
  if block
    method_sym = "__hooks_#{type}_#{quote_method(target_method)}_#{hooks[target_method][type].length}".to_sym
    if scope == :class
      singleton_class.instance_eval do
        define_method(method_sym, &block)
      end
    else
      define_method(method_sym, &block)
    end
  end

  # Adds method to the stack an redefines the hook invocation method
  hooks[target_method][type] << { :name => method_sym, :from => self }
  define_hook_stack_execution_methods(target_method, scope)
end
instance_hooks() click to toggle source
# File lib/dm-core/support/hook.rb, line 152
def instance_hooks
  self.const_get("INSTANCE_HOOKS")
end
method_with_scope(name, scope) click to toggle source
# File lib/dm-core/support/hook.rb, line 388
def method_with_scope(name, scope)
  case scope
    when :class    then method(name)
    when :instance then instance_method(name)
    else raise ArgumentError, 'You need to pass :class or :instance as scope'
  end
end
process_method_added(method_name, scope) click to toggle source

This will need to be refactored

# File lib/dm-core/support/hook.rb, line 210
def process_method_added(method_name, scope)
  hooks_with_scope(scope).each do |target_method, hooks|
    if hooks[:before].any? { |hook| hook[:name] == method_name }
      define_hook_stack_execution_methods(target_method, scope)
    end

    if hooks[:after].any? { |hook| hook[:name] == method_name }
      define_hook_stack_execution_methods(target_method, scope)
    end
  end
end
quote_method(name) click to toggle source
# File lib/dm-core/support/hook.rb, line 396
def quote_method(name)
  name.to_s.gsub(/\?$/, '_q_').gsub(/!$/, '_b_').gsub(/=$/, '_eq_')
end
register_class_hooks(*hooks) click to toggle source

Register a class method as hookable. Registering a method means that before hooks will be run immediately before the method is invoked and after hooks will be called immediately after the method is invoked.

@param hookable_method<Symbol> The name of the class method that should

be hookable

- @api public

# File lib/dm-core/support/hook.rb, line 115
def register_class_hooks(*hooks)
  hooks.each { |hook| register_hook(hook, :class) }
end
register_hook(target_method, scope) click to toggle source

Registers a method as hookable. Registering hooks involves the following process

  • Create a blank entry in the HOOK Hash for the method.

  • Define the methods that execute the before and after hook stack. These methods will be no-ops at first, but everytime a new hook is defined, the methods will be redefined to incorporate the new hook.

  • Redefine the method that is to be hookable so that the hook stacks are invoked approprietly.

# File lib/dm-core/support/hook.rb, line 165
def register_hook(target_method, scope)
  if scope == :instance && !method_defined?(target_method)
    raise ArgumentError, "#{target_method} instance method does not exist"
  elsif scope == :class && !respond_to?(target_method)
    raise ArgumentError, "#{target_method} class method does not exist"
  end

  hooks = hooks_with_scope(scope)

  if hooks[target_method].nil?
    hooks[target_method] = {
      # We need to keep track of which class in the Inheritance chain the
      # method was declared hookable in. Every time a child declares a new
      # hook for the method, the hook stack invocations need to be redefined
      # in the original Class. See #define_hook_stack_execution_methods
      :before => [], :after => [], :in => self
    }

    define_hook_stack_execution_methods(target_method, scope)
    define_advised_method(target_method, scope)
  end
end
register_instance_hooks(*hooks) click to toggle source

Register aninstance method as hookable. Registering a method means that before hooks will be run immediately before the method is invoked and after hooks will be called immediately after the method is invoked.

@param hookable_method<Symbol> The name of the instance method that should

be hookable

- @api public

# File lib/dm-core/support/hook.rb, line 127
def register_instance_hooks(*hooks)
  hooks.each { |hook| register_hook(hook, :instance) }
end
registered_as_hook?(target_method, scope) click to toggle source

Is the method registered as a hookable in the given scope.

# File lib/dm-core/support/hook.rb, line 189
def registered_as_hook?(target_method, scope)
  ! hooks_with_scope(scope)[target_method].nil?
end
reset_hook!(target_method, scope) click to toggle source

Not yet implemented

# File lib/dm-core/support/hook.rb, line 132
def reset_hook!(target_method, scope)
  raise NotImplementedError
end

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